Description

The reason is in !SQLUpdateCompiler.pre_sql_setup(): it checks if there are multiple tables in the query, and if the backend can't do a self select on update ("update_can_self_select" db feature) the pre_sql_setup will run a query to fetch the pks to update. However, in inheritance cases this leads to queries like:

Change History (5)

MySQL generates an extra query in inheritance cases when doing an update.
This results in a test failure when checking for number of queries in
update_only_fields tests. Added a skip temporarily to avoid this test
failure. Refs #18304.